Airplane propeller blade



Oct. 10, 1939. F. LEE'B 2,175,609

v AIRPLANE IROPELLER BLADE Filed Jan. 29, 1938 IN VENTOR.

Zmm M Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE 2 Claims.

created a vacuum tendency and a rush of followup air which abuts against any surface arranged tocatch it, so that there is increased efliciency in the power developed.

I have found that by forming the forward or leading edge of my propeller with a stream line edge merging rearwardly, on the forward or suction side of the propeller in a smooth, convexed outer, surface tapering gradually to the end, and at the other pressure side having said edge turned rearwardly to form an air pocket within the forward or advancing edge of said blade and extending throughout the length thereof, with the face of the blade flat, that Iget a greatly increased emciency. a

I form my improved blade substantially round at its attached end, with a. gradualflaring out into a flattenedblade form and thence to a tapered outer end, with the rolled edge extended along itsv full length and partially around its end, thus providing an air reducing channel along the forward or advancing edge of said propeller, whereby to cause an impact of air on' the working face of said blade to 'the rear of said channel greater than is present in the conventional blade having a flat working face throughout.

In the accompanying drawing I have illustrated one embodiment of my invention, in which g. 1 is a rear face view of a propeller, only one blade being shown; and t Figure 2 is a cross sectional view on line 2-2, of Fig. 1.

Referring now in detail to the drawing, {I

have shown a hub body 3, with three internally. threaded connecting sockets, as l, 4, into which the threaded ends of the propeller blades can 6, having its forward edge formed into a tapering or fish-nose edge in cross section, as'at 'I, Fig. 2, and extending the full length of the forward or advancing edge of the blade, with a part 8 turned or rolled back to form an air-reducing channel 9, extending the full length of the blade and out at the end, as at 9, Fig. l. The wall of the blade terminating at its forward edge in said air-reducing channel is shown straight or flat, as at l0, while the opposite side of said blade is rounded or convexed, as at H, Fig. 2.

It will be seen that the blade in cross section, as seen in Fig. 2, resembles somewhat the forward edge of a stretched out wing of a bird, said forward edge forming an abutment for followup alr'as the blade or wing moves through the air in a well known manner.

I have found from experiments and tests that this form of blade gives increased pulling power, and so far as I am aware I am the first to provide a propeller blade with its forward or leading edge provided with a rolled or turned back portion to form an air-reducing edge or channel along the full length thereof and out at the end so that air abuts into said channel and outwardly toward and to the end with a cam action which gives propulsion to said blade.

In operation my blade, set at the desired angle, bites through the air much like a screw turning into a hard substance. The vacuum tendency set up by the blade, and particularly the forward edge thereof, causes a strong follow-up thrust into and along the channel, while the hooked outer end of said channel will cause a building-up of the small pressure in the channeland thus cause an added forward impulse as the current of air rushes out of the end of the channel.

I prefer to have my blade so constructed that the angle of the blade can be adjusted in the 40 well known manner and as is possible with other blades, but this has nothing to do with the inventive. feature of 'my blade.

On the drawing, I have indicated by small arrows the general course of the air currents around and against the blade in action, only a very few arrows being indicated, and these will be understood by those versed in the art. While I have. shown and described one practical embodiment of my invention, I do not limit it to the details of construction and arrangement shown for illustrative purposes,-except as I may be limited by the hereto appended claims.

' I claim:

1. A propeller for airplanes and the like comprising an elongated blade body, convexed on its forward side in cross section and generally planar on its other, pressure side, and tapering to an end, said body having formed along its leading edge a turned-back portion of hook-like form to form an air-reducing channel along said leading edge, adapted as it is forced through the air to cause a vacuum tendency by said advancing' edge and to cause air impingement against the planar side of said blade, in and along said channel, said turned back portion being curved at the tip of the blade to form a continuation of said channel which extends around the tip of the blade.

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